New theory on flume collapse; work to last 30 days

Workers have removed the damaged areas of Shelbyville's underground flume and will soon install the replacement sections. Meanwhile, evidence pointing to the possible cause behind the collapse was discovered last week.
(T-G Photo by Brian Mosely) [Order this photo]

Meanwhile, new sections of the flume are scheduled to be put in the ground this week.

On Friday, workers plugged up an outbound sewer line from the manhole next to Shelbyville Animal Clinic, but when this was completed, "all of a sudden, sewage came out from underneath the flume," said city manager Ed Craig.

Craig said that workers discovered that the old sewer line, which was recently replaced by contractors for Shelbyville Power, Water and Sewer, was still open, which could have caused storm water runoff to enter the area surrounding the flume.

"It suggests that during the flood event, when there was an awful lot of pressure, that the water came back through the old line and then washed out somewhere underneath the flume," Craig said Monday.

Craig added that this was just a theory, but work was underway Monday to confirm the hypothesis.

"Apparently, when they installed the new line, in the course of switching over between the old line and the new line, they installed a shut-off valve ... and it appears the valve (on the old line) was left open," Craig said.

Craig added he had met with Shelbyville Power representatives Monday and they were on site Monday afternoon with specialized cameras to see if there are any breaks in the old sewer lines.

Current estimates on completion of the work is at 30 days, according to Craig.

Also, the work being done now is currently being paid for by the city, Craig said, but if the reasons behind the collapse are confirmed to be the fault of work done for Shelbyville Power, "then they pay for it," Craig said.

But Craig also added "it's simply premature to assess responsibility."

Speculation over the cause of the collapse has had many looking at work done for Shelbyville Power, which began last November and involved re-laying a sewer line starting beside Shelbyville Animal Clinic, engineer John Freeman of the utility said at the time.

The line was laid eastward under North Brittain Street and runs to Madison Street, where a directional bore went under the main thoroughfare, up to the west side of the old Fix-It Shop. After that, the sewer line crossed Jefferson Street to First Christian Church, where the work ended.

As for the continuing work with the flume, "it's been going great" said public works director Mark Clanton.

All of the damaged steel from the collapsed flume has been removed and work has begun to set down the bedding for the new segments of tubing.

Clanton is hoping the bedding work will be done by Thursday, and then the new flume can be put together and laid underground afterward.

Clanton also says the flume is being installed "pretty much" as it had been in 1963.

While the segment being replaced will be "more structurally sound" with added concrete, Clanton said he does not think there is much more that can be done to prevent another collapse.

"I don't think anybody can say it will never happen again, because you don't know what's going on around this thing," Clanton explained that while they can tell what's happening on the inside of the flume, there is no way to tell what happens on the outside.

But the city is hoping that this section of the flume will not have any more problems once work is completed.